Ok,you have a coupe of options as I see it. It would be possible to drill two holes about a half inch above the handle(blade side),cut, shape and drill the guard to match,(clamping and drilling together would be best), and then pin and peen, or bolt if you have to. Or you could get it welded. I am describing a guard that would be on one side of the blade only.

Or you can get a knife that is designed for the purpose you've intimated. These are made by Cold Steel, and are around a hundred bucks.

__________________GUN CONTROL, I GOT THAT

"I pledge allegiance to the flag of the United States of America, and to the republic for which it stands, one nation under God, indivisible, with liberty and justice for all."

The two enemies of the people are criminals and government, so let us tie the second down with the chains of the Constitution so the second will not become the legalized version of the first. Thomas Jefferson

Am I understanding that you are actually INTENDING on finding yourself in a knife fight situation? You are of course aware that (at least here in the US) when two guys with knives actually fight each other, historically both of them get stabbed and sliced? [Similar stats from WW2 at places like Guadacanal, Tarawa, etc.]